Unless you have a synchronous like setup where you don’t acknowledge data writes unless the remote has aconowledged them first, you will lose data in case your datacenter is hit by a warhead.

Now, there are a few things to consider:

- AWS best practices recommend multiple AZs for workloads and cross-region backups for things like databases and other “stateful” data

- You have to read the fine-print on what AWS offers in terms of recovery: do they reffer to their own infrastructure when they say “you won”t notice” or your data

When Google’s Paris colocation facility was flooded and all AZs there went dark, they sent an email saying “restore from backup in another region and if we can restore your data, we will make it availbale to you”. They did not even issue credits for the downtime.